Oligosaccharides

1. OLIGOSACCHARIDES POLYSACCHARIDES CHEMISTRY OF CARBOHYDRATES- 2 DR.RITTU CHANDEL 04-09-12

2. CARBOHYDRATE MONOSACCHARIDE OLIGOSACCHARIDE POLYSACCHARIDE Two to ten monosaccharide units on hydrolysis More than ten monosaccharide units on hydrolysis HOMOPOLYSACCHARIDE HETEROPOLYSACCHARIDE

3. DISACCHARIDES Most common among oligosaccharides two monosaccharide units (similar or dissimilar) held by glycosidic bonds properties – water soluble, sweet to taste MALTOSE,LACTOSE,ISOMALTOSE,CELLOBIOSE SUCROSE,TREHALOSE

4. DISACCHARIDES CONSTITUENTS REDUCING (+)- MALTOSE GLUCOSE+GLUCOSE (+)- LACTOSE GLUCOSE+GALACTOSE (+)-CELLOBIOSE GLUCOSE+GLUCOSE MELIBIOSE GLUCOSE+GALACTOSE NON REDUCING (+)-SUCROSE GLUCOSE+FRUCTOSE TREHALOSE GLUCOSE+GLUCOSE -

5. MALTOSE (malt sugar)

6. maltose Digestion of starch by amylase,germinating seeds, malt Action of maltase or dilute acid on maltose gives glucose units Fermented by yeasts PROPERTIES: Reducing sugar, soluble and sweet taste Sunflower shaped osazones Mutarotation Exhaustive methylation of all free –OH group,followed by hydrolysis of glycosidic linkage gives 2,3,4,6-tetra-O-methyl-D-glucose and 2,3,6-tri-O-methyl-D-glucose

7. LACTOSE (milk sugar)

8. lactose In milk Action of intestinal lactase on lactose gives glucose and galactose PROPERTIES: Reducing sugar Powder puff or hedgehog or badminton ball shaped osazone Not very soluble and not so sweet dextrorotatory At body temperature exists as an equilibrium mixture of α and β forms in 2:3

9. lactose Fearon’s test lactosuria

10. Sucrose (table sugar)

11. sucrose In sugar cane,sugar beet,pineapple,carrot roots Major carbohydrate in photosynthesis (in roots,tuber,seeds ) Most abundant among naturally occuring sugars Distinct advantage:storage and transport forms Action of Intestinal sucrase on sucrose gives glucose and fructose

12. sucrose PROPERTIES Non reducing No osazone formation Very soluble and very sweet Specific sucrose test USE Sweetening agent in food industry

13. Inversion of sucrose Dextrotatory sucrose (+66.5˚) on hydrolysis becomes levorotatory Equimolar mixture of glucose and fructose is invert sugar Honey contains invert sugar (sweeter than sucrose) Sucrose sucrase α -D- glucopyranose +112.2 ˚ β -D- glucopyranose +18.7 ˚ β -D- fructofuranose β -D- fructopyranose -133 ˚ α -D- fructopyranose -21˚

14. Isomaltose , gentiobiose ISOMALTOSE - Glucose + glucose α (1 → 6) partial hydrolysis of glycogen and starch gives it oligo-1,6-glucosidase in intestinal juice hydrolyses GENTIBIOSE - β (1 → 6) glucose +glucose

15. TREHALOSE Non reducing sugar Distinctive sweet taste Major sugar of insect endolymph

16. cellobiose Virtually no taste Not fermented by yeast Obtained by hydrolysis of cellulose Indigestible by humans Β (1→ 4) linkage is represented as zigzag but one glucose is actually flipped over relative to other

17. lactulose A ketodisaccharide Fermented by intestinal bacteria Used in osmotic laxative, in hepatic encephalopathy α -D- galactopyranosyl -(1 → 4)- β -D- fructofuranose

18. trisaccharides RAFFINOSE in sugar beets O- α -D- galactopyranosyl -(1 → 6)-0- α -D- glucopyranosyl -(1 → 2)- β -D- fructofuranoside MELEZITOSE in sap of some coniferous trees O- α -D- glucopyranosyl -(1 → 3)-O- β -D- fructofuranosyl -(2 → 1)- α -D- glucopyranoside

19. tetrasaccharide STACHYOSE Galactose+galactose+glucose+fructose PENTASACCHARIDE VERBASCOSE Galactose+Galactose+galactose+glucose+fructose

20. polysaccharides( glycans ) Repeat units of monosaccharides or their derivatives,held by glycosidic bonds Relatively or totally insoluble,tasteless LINEAR BRANCHED

21. POLYSACCHARIDES HOMOPOLYSACCHARIDE HETEROPOLYSACCHARIDE GLUCAN FRUCTOSAN MANNANS

22. HOMOPOLYSACCHARIDE STORAGE POLYSACCHARIDE STRUCTURAL POLYSACCHARIDE STARCH GLYCOGEN DEXTRANS INULIN CHITIN CELLULOSE

23. STARCH

24. starch Most important dietary source of man and animals Carbohydrate reserve of plants In potato,tapioca,rice,wheat Deposited in form of granules in cytoplasm STARCH GLUCOSE Acid hydrolysis

25. AMYLOSE Amylose α(1 → 4) Not soluble in water Forms hydrated micelles Gives blue colour with iodine Helical coil with 6 glucose/turn Amylopectin α (1→4) but branching points are α (1→ 6) Most abundant in plants Gives red violet colour with iodine

26. amylases Two types- α and β Both hydrolyse only α - glycosidic bonds α - amylase = α (1→4)-glucan-4-glucanhydrolase β -amylase = α (1→4)-glucan-4-maltohydrolase Debranching enzyme- α (1→6)- glucosidase or α (1→6)- glucan-6-glucanhydrolase

27. BREAKDOWN PRODUCTS OF STARCH AMYLOPECTIN VIOLET ERYTHRODEXTRIN RED ACHRODEXTRIN NO MALTOSE NO STARCH BLUE

28. GLYCOGEN Main storage polysaccharide of animal cell Abundant in liver and skeletal muscle Also in plants that do not have chlorophyll Animal starch Immediate source of energy Dextrorotatory Not readily soluble in water and forms opalascent solution Not destroyed by hot strong KOH or NaOH With iodine gives deep red colour

29. glycogen Glycogen is used as energy source,glucose units are removed one at a time from non reducing ends Glucose is not stored in monomeric form Starch and glycogen are heavily hydrated

30. dextran Polymer of D-glucose Synthesized by leuconostoc mesenterides Dental plaque Synthetic dextrans Branched polysaccharide of D-glucose Branching at 1 → 2, 1 → 3, 1 → 4 or 1 → 6 Plasma volume expander

31. inulin D-fructose residues in β (2→1) In dahlia,garlic,onion,dandelion White, tasteless powder Levorotatory No dietary importance in humans Used for estimation of body water volume(ECF), assesing kidney functions through means of GFR

32. CHITIN Second most abundant polysaccharide

33. CELLULOSE Not attacked by α or β amylase

34. cellulose Every other glucose molecule is flipped over other due to β linkages Parallel orientation is favoured by intermolecular hydrogen bond X-ray diffraction of cellulose shows bundles of parallel chains to form fibrils Not digested by mammals

35. cellulose Most abundant structural polysaccharide in plants Cotton fibers are pure cellulose Insoluble in water D-glucose CELLULOSE partial hydrolysis Cellobiose 2,3,6-tri-O-methyl glucose Complete hydrolysis Exhaustive methylation Strong acids

36. biblography LEHNINGER HARPER TALWAR BHAGVAN DEBJYOTI DAS

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